TimeCalendarPropertyType, TimeCalendarEraPropertyType TimeClock Calendars and clocks .1 Overview

166 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.

14.4.4.5 TimeClockPropertyType

gml:TimeClockPropertyType provides for associating a gml:TimeClock with an object: complexType name=TimeClockPropertyType sequence minOccurs=0 element ref=gml:TimeClock sequence attributeGroup ref=gml:OwnershipAttributeGroup attributeGroup ref=gml:AssociationAttributeGroup complexType 14.4.5 Ordinal temporal reference systems 14.4.5.1 Overview In some applications of geographic information — such as geology and archaeology — relative position in time is known more precisely than absolute time or duration. The order of events in time can be well established, but the magnitude of the intervals between them cannot be accurately determined; in such cases, the use of an ordinal temporal reference system is appropriate. An ordinal temporal reference system is composed of a sequence of named coterminous eras, which may in turn be composed of sequences of member eras at a finer scale, giving the whole a hierarchical structure of eras of varying resolution. An ordinal temporal reference system whose component eras are not further subdivided is effectively a temporal topology complex constrained to be a linear graph. An ordinal temporal reference system some or all of whose component eras are subdivided is effectively a temporal topology complex with the constraint that parallel branches may only be constructed in pairs where one is a single temporal ordinal era and the other is a sequence of temporal ordinal eras that are called members of the group. This constraint means that within a single temporal ordinal reference system, the relative position of all temporal ordinal eras is unambiguous. The positions of the beginning and end of a given era may calibrate the relative time scale.

14.4.5.2 TimeOrdinalReferenceSystem, TimeOrdinalEra

gml:TimeOrdinalReferenceSystem implements ISO 19108 TM_OrdinalReferenceSystem see D.2.5.10 and ISO 19108:2002, 5.3.4 by adding one or more gml:component properties to the generic temporal reference system model. It is declared as follows: element name=TimeOrdinalReferenceSystem type=gml:TimeOrdinalReferenceSystemType substitutionGroup=gml:TimeReferenceSystem gml:TimeOrdinalReferenceSystem may be used in any position that a gml:TimeReferenceSystem is valid. Its content model is defined as follows: complexType name=TimeOrdinalReferenceSystemType complexContent extension base=gml:TimeReferenceSystemType sequence element name=component type=gml:TimeOrdinalEraPropertyType maxOccurs=unbounded sequence extension complexContent complexType gml:TimeOrdinalEra implements ISO 19108 TM_OrdinalEra see D.2.5.10 and ISO 19108:2002, 5.3.4. Its content model follows the pattern of gml:TimeEdge see 14.3.2.8, inheriting standard properties from gml:DefinitionType see 15.2.1, and adding gml:start, gml:end and gml:extent properties, a set of Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 167 gml:member properties which indicate ordered gml:TimeOrdinalEra elements, and a gml:group property which points to the parent era. This is declared as follows: element name=TimeOrdinalEra type=gml:TimeOrdinalEraType complexType name=TimeOrdinalEraType complexContent extension base=gml:DefinitionType sequence element name=relatedTime type=gml:RelatedTimeType minOccurs=0 maxOccurs=unbounded element name=start minOccurs=0 type=gml:TimeNodePropertyType element name=end minOccurs=0 type=gml:TimeNodePropertyType element name=extent type=gml:TimePeriodPropertyType minOccurs=0 element name=member type=gml:TimeOrdinalEraPropertyType minOccurs=0 maxOccurs=unbounded element name=group type=gml:ReferenceType minOccurs=0 sequence extension complexContent complexType The recursive inclusion of gml:TimeOrdinalEra elements allow the construction of an arbitrary depth hierarchical ordinal reference schema, such that an ordinal era at a given level of the hierarchy includes a sequence of shorter, coterminous ordinal eras. EXAMPLE The example below shows a portion of the geological time scale depicted as an ordinal reference system: gml:TimeOrdinalReferenceSystem gml:id=GeologicalTimeScale gml:description xlink:href=ftp:ftp.iugs.orgpubiugsiugs_intstratchart.pdf gml:nameGeological time scalegml:name gml:domainOfValidityEarthgml:domainOfValidity -- Earlier eras omitted -- gml:component gml:TimeOrdinalEra gml:id=Cenozoic gml:nameCenozoic Eragml:name gml:start xlink:href=basePaleocene gml:end xlink:href=now gml:member gml:TimeOrdinalEra gml:id=Tertiary gml:nameTertiary Periodgml:name gml:start xlink:href=baseTertiary gml:end xlink:href=basePleistocene gml:member gml:TimeOrdinalEra gml:id=Paleogene gml:namePaleogene sub-periodgml:name gml:start gml:TimeInstant gml:id=basePaleogene gml:timePosition frame=geologyMa65.0gml:timePosition gml:TimeInstant gml:start gml:end xlink:href=baseNeogene gml:member gml:TimeOrdinalEra gml:id=Paleocene gml:namePaleocene Epochgml:name gml:start xlink:href=basePaleogene gml:end xlink:href=baseEocene gml:TimeOrdinalEra gml:member gml:member gml:TimeOrdinalEra gml:id=Eocene gml:namePaleocene Epochgml:name gml:start